OCTG is short for Oil Country Tubular Goods and refers to the pipes used in oil and gas extraction. The API 5CT standard covers the OCTG coupling, threading, and materials connections used in drilling operations. It includes instructions on dimensions, sizes, wall thicknesses, materials grades, tolerance limits, and performance requirements. The API 5CT is widely used in the oil and gas industry for both onshore and offshore drilling operations. OCTG manufacturers need to adhere to the standards set out in the API 5CT to ensure that their products are compatible with the oil and gas industry’s equipment and operations. By following the API 5CT, manufacturers can be confident that their OCTG products will be able to meet the demands of the oil and gas industry.
Why choose tuspipe?
Since 1998, Tianjin United Steel Pipe Co., Ltd (TUSPIPE) has been committed to supplying high-quality line pipes.
With over 500,000 tons annual production capacity, the company serves various fields and industries, such as oil & gas exploitation and transmission, ship & auto-building, water & electricity, environmental protection, mechanical engineering, infrastructure construction and etc.
TUSPIPE places a premium on product quality and rigorous product quality control. In order to maintain good product quality, the company has established a Test & Inspection Center since 2004. With a series of state-of-the-art tests and inspection equipment, the test & inspection center is able to perform the tensile tests, hydro tests, impact tests, DWTT, etc.
Steel Grade of API 5CT Standard
- Group 1: All casing and tubing in Grades with H, J, K, N and R
- Group 2: All casing and tubing in Grades with C, L, M and T
- Group 3: All casing and tubing in Grade P
- Group 4: All casing in Grade Q
Dimensions and Sizes of API 5CT Casing and Tubing
- Specification & Size of API 5CT Tubing
|DN||O. D.||Weight||W. T.||End Processing|
|Non-upset coupling-thread||Upset coupling-thread||Steel Grade|
|P——Plain；N—— Non-upset coupling-thread；U—— Upset coupling-thread； L——Integral|
- Specification & Size of API 5CT Casing
|DN||O. D.||Weight||W. T.||End Machining Form|
|P——Plain；S——Short-thread；L——Long-thread；B——Buttress thread；E——Extreme thread|
Chemical Composition (%) of API 5CT
Mechanical Properties of API 5CT
API 5CT Dimensional Deviation
|Out Diameter||D ≤ 101.60mm||± 0.79mm|
|D ≥ 114.30mm||+ 1.0%, -0.5%|
|Mass (Single Lengths)||+6.5%, -3.5%|
Length Range of API 5CT
|Item||Scope 1||Scope 2||Scope 3|
Test and inspection of API 5CT Tubing and Casing
- Hydrostatic Test
Hydrostatic testing is a critical quality control measure during the production of steel pipe. The purpose of the hydrostatic test is to verify that the seam welds and pipe body can withstand the required internal water pressure without leaking. To conduct the test, water is pressurized and injected into the pipe. Once the water pressure reaches the specified level, the pipe is subjected to a thorough examination for leaks. Any leaks that are found are repaired and the hydrostatic test is repeated until the pipe passes inspection. This process ensures that the finished product can safely transport water or other fluids under high pressure without leaking.
- Bend Test
During the production of an API 5CT tubing and casing pipe, a bending test is conducted to ensure the quality of the weld. This test involves taking a sample of the steel pipe and subjecting it to a bending force. The results of the test are then evaluated to determine if there are any cracks in the weld. If no cracks are found, the pipe is deemed to be of acceptable quality. However, if cracks are found, the pipe is rejected and must be repaired or replaced. The bending test is an important part of the production process, as it helps to ensure that the final product is of high quality and will perform as intended.
- Flattening Test
Flattening tests are typically performed during the quality control testing of steel pipes, such as those produced according to the API 5CT specification. The flattening test is used to assess a sample pipe’s resistance to longitudinal deformation (i.e. crack growth) and its ability to maintain its shape under stress. The test is conducted by first welded a ring onto one end of the pipe sample. The other end of the sample is then placed in a jig, which compresses the entire length of the pipe along its longitudinal axis. Once the desired compression is achieved, the jig is released and the sample is removed for inspection. Any cracks or deformations that have occurred during the test are then documented and analyzed. The results of the flattening test can be used to assess the quality of the pipe and its suitability for use in various applications.
- CVN Impact Test
When it comes to tubing and casing pipe production, the impact test is an important quality control measure. Also known as the Charpy test, this test is used to assess a material’s ability to withstand impact. The test involves striking a specimen with a hammer and then measuring the amount of energy that is absorbed. The results are then compared to a standard to determine whether the material meets the required specification. There are three main areas that are tested during impact testing: the pipe body, the weld sea, and the heat-affected zone. By understanding the importance of this test, manufacturers can ensure that their steel pipes meet the required standards for strength and durability.
API 5CT Pipe Ending Processing
- Flat End / Plain End
A plain end, also known as a flat end or square cut, is a type of steel pipe that has a flat end rather than a beveled or threaded end. Plain end pipes are more common in larger diameter pipes and are typically used for carrying fluids under high pressure. One advantage of plain end pipe is that it is easier to weld or connect to other types of pipe. However, plain end pipe is less able to withstand external forces, such as those from wind or waves, and is more susceptible to damage from impacts. As a result, plain end pipe is often used in applications where it will be buried or otherwise protected from the elements.
- Threaded End
Casing is a steel pipe that is used to line the borehole of a drilling well. It is important to use casing in order to prevent collapse of the borehole and to protect the equipment that is being used. Casing is also used to keep out water, gas, and oil from entering the well. The threaded end on a casing pipe is used for making a connection with a screw. This type of connection is known as a threaded joint. In order to make this connection, a casing coupler is used. The coupler is screwed onto the end of the pipe and then the two pipes are connected together with a screw.
- Rounded Nose
A rounded nose on a casing pipe is simply a threaded connection that has been machined to have a rounded, rather than flat, end. This type of connection is often used when space is limited, such as in tight corners or other difficult-to-reach areas. In addition, rounded noses are less likely to snag on surrounding objects, making them ideal for use in high-traffic areas. Although they are more expensive than traditional threaded connections, the increased safety and durability of rounded noses make them well worth the investment.
What is API 5CT OCTG?
Oil country tubular goods (OCTG) is a family of steel pipe products used in the drilling, completion, and production of oil and gas wells. And, API 5CT is the standard for the group of products. OCTG casing and tubing are essential elements in the well construction process, as they provide support and protection for the well bore. Casing is installed first, followed by tubing. The casing is typically made of steel or other strong materials that can withstand the high pressure and temperature of the reservoir. Tubing is also made of steel, but it is thinner walled and carried inside the casing. OCTG products are manufactured to meet specific specifications that are based on the type of well being drilled. For example, sour service casing must be able to resist corrosion from hydrogen sulfide gas. Deepwater casing must be able to withstand the high pressures found at great depths. Ultimately, OCTG products play a vital role in ensuring the safety and efficiency of oil and gas drilling operations.
What is the Difference between API 5CT Casing and Tubing?
API 5CT casing is a tube that is placed in a wellbore in order to protect the wellbore from contamination. Casing is also used to stabilize the wellbore and keep it secure. Drilling and casing operations occur alternately, with the drill string being removed at predetermined intervals. API 5CT tubing is used to carry petroleum from the depths of the well to the surface. Oil and gas may sometimes self-elevate to the surface; however, pumps are typically required in order to bring these fluids to the surface. Tubing typically has a smaller diameter than casing. The main purpose of tubing is to transport petroleum from the well to an external location.